Synchronous augmenter for resojet motors



Feb. 17, 1953 J. Y. DUNBAR SYNCHRONOUS AUGMENTER FOR RESOJET MOTORSFiled Aug. 2. 1945 'INVENTOR JAMES Y DU NBAR ATTORNEY Patented Feb. 17,1953 SYNCHRJONOUS AUGMENTER FOR RESOJET MOTORS James Y. Dunbar, UnitedState Navy Application August 2, 1945, Serial No. 608,542

8 Claims.

(Granted under This invention relates to an auxiliary synchronousaugmenter for jet propulsion devices such as operate cyclically or inresonance.

An object of this invention is toprovide an augmenter that increases thecompression and consequently the efficiency of jet propulsion de: vicesoperating cyclically or in resonance.

A further object of this invention is to provide a device whereby theexhaust of one motor operating cyclically or in resonance augments thecompression of another similar operating motor.

Other objects and advantages of this invention will become apparent asthe discussion proceeds and is considered in connection with theaccompanying claims and drawing wherein like characters of referencedesignate like parts in the several views and wherein:

Fig. I is a schematic view of a reso-jet motor showing the augmenterembodied in this invention;

Fig. 11 is a longitudinal section view of a resojet motor showing onemodification of the augmenter embodied in this invention;

Fig. III is a schematic view of another modification of the augmenterembodied in this invention.

Referring now to the drawing, wherein for the purpose of illustration,are shown preferred'embodiments of this invention, the numeral 4designates the tail pipe or resonant exhaust tube of a conventionalreso-jet motor. The numeral 5 designates an explosion chambercommunicating with the said tail pipe, having a spark ignition means 6such as a. conventional spark plug. The end of the said explosionchamber 5 is provided with an end plate 1, carrying a rotating valve 8which meters fuel and air or air only into the said chamber 5. In themodification shown in Fig. I the valve 8 is any conventional type ofmechanically operated high speed valve such as a rotating valve drivenby a synchronous motor I. An auxiliary passage opening or hole 9,disposed toward the end of the tail pipe 4, is adapted to receive a tailpipe ll of a smaller synchronously operated auxiliary reso-jet motordesigned for the same operating frequency as the large motor, as shown.The said tail pipe ll carries a combustion chamber 12 provided with avalve l3 driven also by the synchronous motor. A suitable mechanicallink-age l4 connects the synchronous valve 13 to the synchronous valve 8phased approximately 180 degrees therefrom. The phase angle issusceptible to being varied by relative phase adjustment coupling 29 toprovide the optimum efficiency and firing times for the two 1 motors.

Title 35, U. S. Code (1952),

sec. 266) In the modification shown in Fig. 11 the tail pipe orresonance tube 4, the combustion chamber 5, the electric combustionfiring means 6 and end plate 1 are the same as in Fig. I. Ihe valves I5,afiixed to the plate I, are of the vibrating or reed type. A hole 9disposed near the end [0 of the tail pipe 4, as in Fig. I, has a tailpipe II, and a much smaller synchronously operated inotor affixedthereto, disposed at an angle, substantially as shown. Afiixed to thetail pip'elll is a combustion chamber [2 carrying electric ignitionmeans it, as shown. Vibrating valves I! of the reed or resilient typeare providedin the end of the combustion chamber 12 to admitair or airand fuel.

In the modification of this invention shown in Fig. III the numerals I8and I9 designate'the tail pipes of two identical reso-jet motors havingcombustion chambers 20 and 2!, respectively, affixed thereto. Air isadmitted to the combustion chambers through valves 23, of anyconventional design. Conventional spark plugs or other electric firingmeans 24 are provided in the combustion chambers 20 and 2| to fire thecharges. A U tube 25 disposed in the tail pipes l8 and i9, and in opencommunication therewith, is affixed to the said tail pipe 18 at 26 andto the said tail pipe R9 at 27. It is to be noted that the U is turnedtowards the combustion chambers 20 and 2 I. The motors are rigidlyafi'ixed together at 28 in any conventional manner, s by welding vor thelike.

In operation the auxiliary synchronousaiigmenter as shown in Figs. I andII, consists of a dual resonant jet'motor, the largerunit being thepropulsion unit and the maller the compressor unit, each unit augmentingthe compression of the other. 1

If the gas in the motor (due to theexplosion in the combustion chamber),is excited into motion, it tends to oscillate at the natural frequencyof the unit until brought to rest by damping or friction. If theexplosion taking place in the explosion chamber has the ame periodicityas the natural frequency of the motor the motion "of the gas in the tailpipe will build up to a maximum value limited only by friction ordamping or by the constant governing the inertance' and compliance ofthe resonator system. Friction damping may be reduced to a minimum byproper shaping and smoothing the inner surface'of the motor parts. Butthe inertance and compliance of the system, which determines the naturalfrequency characteristics, are both functions of gas density whichvaries during the cycle. Should the gas mass in the tailpipe beconsidered as a piston N moving outwardly, the maximum restoring forceor pressure attainable will be the ambient atmospheric pressure, if acomplete vacuum can be created. If the piston moves inwardly, thecompression is adiabatic and approaches infinity. *Sh'ouldzinexplosive'charge be introduced into the chamber at the end of theoutward stroke, the weak restoring force, drawing the piston (or gas)back into the tail pipe,causes very little pre-compression of the fuelmixture. results in loss of both power and elficiency. But if anauxiliary compressor be used to provide a high compression of the chargeor mixture, the thrust and efliciency is improved.

When this auxiliary compressor is itself a smaller, similar resonating.jet motor, its fuel mixtur is compressed by 'themain. motor discharge,and the main.motor in turn receives its vcompression from the firing ofthe auxiliary "motor.

Thus-a concatenation takes place be- "tween' thetwo motors to achieveahigher overallefiiciency.

I These two motors maybe kept in proper phase relation toeach'other bymeans of mechanically driven'valvesof any conventional type (specific"titail's'of'which are'not shown here), interconfnected todrive at thesame frequency, as illustrated in Fig. I, or when using a motor having*avibrating orree'd typevalve as shown in Fig.

"-"lIythetwomotors are designed so that they have 'ra'ngement of partsmay be resorted to, without I departing from the spirit of my invention,or 'the'scope ofth'e subjoined claims.

The invention described herein may be manu- Ff'ac'tured'a'nd used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

"What I claim is:

1. An augmenter 'forreso-j'et motors comprising a plurality of 'r'es'oetmotors each "having a combustion chamber with a fluid inlet, anintermittently operable inlet valve upstream of said combustion chamber,a tailpipe having an outlet and in alignment with the combustionchamber, a conduit opening through the wall of the tail .pipe of :one ofsaid -motors downstream of its combustion chamber and having alongitudinal axis disposed at an acute angle and extending.rearwardly-of the tail pipe, said conduit being connected to the tailpipe of another of said motors,'synch-ronizing means for oppositelyphas- 'ing said :two motors for mutual alternate augmentation of thecompression steps in each of said moto'rs by the discharging gases fromexauxiliary passage means "in the wall or at least one exhaust tubethrough which exhaust gas from the explosion chambers of at least tworeso-jet motors is directed into the exhaust tube and toward theexplosion chamber of the other, the exhaust tube of at least one of saidreso-iet motors being open at one end forescape of exhaust propulsiongas, and synchronizing means for firing the said two reso-jet motorsalternately.

3. The combination set forth in claim 2 further defined i'n'that theauxiliary passage means is shaped to reverse the direction of movementof exhaust gas'passing through it.

4. An augmenter for a main reso-jet motor having a combustion chamber, aresonant exhaust tube and a mechanically driven valve communicating withsaid chamber, comprising a smaller auxiliary reso-jet motor having acombustion chamber and a mechanically driven valve municating with saidchamber, comprising a smaller auxiliary reso-jet motor having acombustion chamber and a mechanically driven valve communicating withsaid chamber, a driving linkage synchronously connecting the firstmentioned valve to the said mechanically driven valve, and a resonantexhaust tube afiixed to the exhaust tube of the said main motor, saidsmaller auxiliary motor being timed to fire out of phase with the mainmotor.

6. In combination, a plurality of reso-jet motors each having acombustion chamber with a fluid inlet upstream thereof, an igniter andan intermittently operable inlet valve for said combustion chamber, anda tail pipe connected to the combustion chamber, the tail pipe of one ofsaid reso-jet motorsbeing open at one end and-having an opening alongits length downstream of-said combustion chamber, said opening formingthe entrance of an auxiliary passage to the tail .pipe of a secondreso-jet motor, and means for firing the two named motors sequentiallyso that .part

ofthe exhaust gas from the explosion in the-combustion chamber of thefirst named motor will move into the tail pipe of the second namedmotor.

7. In combination, a plurality of l'GSO-rjfit motors leach-having afluid inlet, 'a combustion chamber, an intermittently operable inletvalve for said combustion chamber, and a tail pipe aligned with thecombustion chamber, the tail valves of both named motors to operate in-sequence so that part of the exhaust gas from the explosions in thecombustion chamber of 'the said motor having the open tail pipe willmove into the tail pipe-of the second motor, and means for firing thesecond motor after exhaust gas has moved into its tail pipe.

8. In a -j etengine, a first reso-jetmotor having "a combustion chamber,"an air inlet o' mm lupstream of said chamber, a tail pipe in alignmentwith said combustion chamber to receive and convey products ofcombustion from said chamber to the atmosphere, and means operativelyconnected with said chamber for igniting fuel in said chamber, a secondreso-jet motor companion to said first reso-iet motor, said second motorincluding a combustion chamber with a tail pipe connected. therewith anda fluid inlet opening upstream of the last-mentioned chamber, saidfirst-mentioned tail pipe having a lateral opening therein downstream ofsaid first-mentioned combustion chamber, and, said second motor tailpipe being communicated with said lateral opening, said second motorcombustion chamber hav-- ing ignition means for said second motor timedto operate during the compression stage of actuation of said firstreso-jet motor so that exhaust gas from said second motor passes throughsaid lateral opening and into the first motor tail pipe to augment thecompression in said first motor. JAMES Y. DUNBAR.

6 REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

